1. Field of the Invention
The present invention relates to a method for producing a strip the width of which is defined by the two longitudinal edges thereof, which is made of at least one first metallic or predominantly metallic material, and in which the region, across which the first material extends, is provided with a boundary area that extends in staggered manner between the two longitudinal edges over the cross-section of the strip, as defined in the preamble of Claim 1. Strips of that kind are known, for example, in the form of bimetal strips where a carrier strip, consisting of a first metal, comprises a longitudinal groove filled with a strip of a second material. Such an arrangement is described as strip plating or inlay plating. Further, there have been known metal strips where a carrier strip consisting of a first metal is stepped along one of its longitudinal edges and the step is filled with a strip consisting of a second material. Such an arrangement is described as front edge plating. Further, there have been known strips that comprise both an inlay plating and a front edge plating. It has been known to produce plated strips of that kind by starting out from a carrier strip of flat rectangular cross-section, forming in that carrier strip the required number of grooves and/or steps by cutting operations (milling, stripping or scraping, with milling being preferred) and replacing the material removed by the machining operation by a corresponding number of strips consisting of one or more other metals or alloys. Connecting the carrier strip with the fitted strips is then effected by cold-roll plating or hot-roll plating, during which process the length of the strip increases as a function of the selected reduction per pass of the rolling operation.
2. Description of the Related Art
Variations in dimension in the region of an inlay plating and a front edge plating are determined essentially by the variation in dimensions resulting from the respective cutting operation. Variations in dimension resulting from the respective cutting operation occur in the same order of magnitude in the roll-plated strip. The same applies correspondingly to the production of strips provided with one or more longitudinal grooves or steps that are not filled with another metal by roll plating.
Variations in dimension are considered as a problem especially in strip-shaped semi-finished products for electric laboratory resistors. It has been known to produce such a strip-shaped semi-finished products by placing a strip consisting of the resistor material, for example of the alloy manganine, on two copper strips, arranged at a spacing in parallel one to the other, so that the first-mentioned strip bridges the space between the two copper strips. The strips arranged in this manner are then bonded either by roll seam welding or by electron beam welding. Apart from the fact that such a production method is relatively costly, variations with respect to the spacing of the copper strips, and variations with respect to the dimension and quality of the welding seams may lead to undesirable fluctuations in resistance of the laboratory resistors produced from the semi-finished strip material by punching. Further, it is an undesirable effect of that process that the laboratory resistors present a step between the manganine and the copper on the side on which the manganine strip is welded onto the copper strips. Such a step could be avoided by milling a step into the two copper strips, along one of their edges, that corresponds in height to the thickness of the manganine strip and which is then filled up again by fitting the manganine strip. The manganine strip placed on the two steps of the copper strips can then be bonded to the latter by roll seam welding or electron seam welding. The undesirable step between the manganine surface and the copper surface could be removed in this way—though at the high price of two milling operations and without reducing the fluctuation of the resistance values.
From JP 550 400 11 A it has been known to produce plates with grooves by placing wires, consisting of a hard material, on a sheet consisting of a softer material, and by then subjecting the assembly to a subsequent rolling operation. The wires thereby dig into the sheet and can then be removed again.
From JP 610 173 08 A it has been known to place two metal strips one on top of the other and to bond them together by rolling.
GB 2 237 227 A describes a method where a plurality of metal plates are placed one on top of the other, are subjected to a rolling operation, and are then wound up separately.